1. MANSE Midterm Review Organic Spintronics Current team members Franklyn Burke (graduate student, 2007-) Huesyin Tokuc (graduate student, 2008-) Prof. Greg Szulczewski SFI Walton Fellow 2008-2009 “Spin Electronics with Organic Materials”

2. MANSE Midterm Review Research Acitivities Growth of organic microcrystals and nanowires by physical vapor deposition Characterization of organic wires by SEM, TEM, XRD, PL, EPR, FT-IR, and SQUID magnetometery Fabrication of nanogap electrodes Set-up high impedance probe for magnetotransport studies on crystalline organic semiconductors Construction of UHV chamber for spin valve growth Transport measurements on Alq 3 based MTJs

3. MANSE Midterm Review Organic Crystal Growth Al doped 8-hydroxyquinoline rubrene Cu phthalocyanine (CuPc) Physical vapor deposition Alq3

4. MANSE Midterm Review SQUID Magnetometery of Alq 3 The concentration of paramagnetic (S= ½) defect centers in Alq 3 is estimated to be: 4 x10 -4 /formula unit. This yield an average defect separation of ~ 11 nm. Al-doped 8-hydroxyquinoline nanowires Unshaved material scavenges Fe from the stainless steel die!

5. MANSE Midterm Review Alignment of crystals on electrodes Al-doped 8-hydroxquinolinerubrene a = 24.936 Å, b = 28.551 Å, c = 3.787 Å a = 14.44 Å, b = 7.18 Å, c = 26.97 Å Nano gap Largest μ along B axis

6. MANSE Midterm Review Fabrication of nano gap electrodes UV optical lithography to prepare Deposit Pt contacts on nanowire Hall bar by electron beam deposition Focused–ion beam etching to produce trench

7. MANSE Midterm Review Magnetotransport in organic nanowires Al-doped 8-hydroxyquinoline NiFe electrodesAu electrodes Tunneling NNH VRH

8. MANSE Midterm Review Rubrene crystals on NiFe electrodes Semiconducting behavior σ = σ o exp[-(T M /T) 1/(1+d) d =1 and T M ~ 235 K 280nm gap

9. MANSE Midterm Review Magnetotransport for rubrene on NiFe MR proportional to T -2.25 Negative MR scales linearly at high H Positive MR seen at low H No MR observed using Au electrodes Negative MR is predicted to scale as T -1.5 for 1D VRH* *Nguyen et al. JETP 1985, 62, 1021 300nm gap 70 K

10. MANSE Midterm Review TMR characteristics of 24 x 24μm 2 junctions 2.5 nm Al 2 O 3 2.5 nm Al 2 O 3 / 1nm Alq 3 The MTJ Stack: SiO 2 /Ta(30)/CoFe(5)/Barrier/CoFe(3)/IrMn(10)/Ta(5)/Pt(5)

11. MANSE Midterm Review On-going work Metal phthalocyanine (MPc) films and crystal growth M= Mn, Fe, Co, Ni, Cu, and Zn Deposition of vertical spin valves in new UHV chamber

12. Future work MANSE Midterm Review Fabricate lateral spin valves with different coercivity electrodes and gap separation Vertical spin valves with crystalline MPc’s e.g. CoFe/MgO/MPc/LiF/Co Magnetometery, spectroscopy, and microscopy of FM/organic and organic/FM interfaces